At present, the problems of improving the fuel economy, reducing the fume emission and toxic ehxaust of internal combustion engines have become very urgent. A great number of theoretical studies, experiments and inventions were directed toward the solution of these problems.
One line in this direction was to increase the ratio of the volume of the combustion chamber to the compression volume. An increase in this ratio is normally attained by reducing the compression volume, which can in turn be achieved through reducing the volume determined by the clearance or space between the piston and the cylinder head, the volume of the valve seat recesses, the volume between the piston and cylinder when the piston is at top dead center, and the volume occupied by a gas space the presence of which is determined by that due to structural and technological considerations the cylinder holes in the cylinder head gasket are greater in diameter than the cylinder bores. As a rule, the abovementioned volumes are selected in the course of experimental engine improvement and therefore can be reduced exclusively through the application of specific structural modifications. One of the locations where such structural novelties can be applied is the gas space (cylinder head joint) of the engine.
There is known an internal combustion engine (cf. USSR Inventor's Certificate No. 482,561; IPC F 02 B 11/00) in which for reducing the specific fuel consumption, fume emission and toxic exhausts, as well as for a more reliable and dependable service of the cylinder head gasket, the upper end face of a cylinder liner is provided with an annular groove in which a shaped metal ring is placed.
However, this construction fails to provide for complete filling of the volume of the gas space in the cylinder head joint, since a free area remains between the cylinder head and the upper end face of the cylinder liner's fire shoulder. Also, the abovedescribed construction requires the use of special cylinder liners; in other words, it cannot find application in internal combustion engines already in service.
There is further known an internal combustion engine (cf. USSR Inventor's Certificate No. 848,722; IPC F 02 F 11/00 and F 16 J 15/06) wherein for the same purpose a ring element of a soft material is placed on a cylinder liner shoulder, this shoulder being provided with spiral grooves in which the material of the ring element is pressed when the cylinder head is mounted on the engine block.
Inherein in the above construction is a disadvantage residing in that the entire volume of a gas space in the cylinder head joint, that is the space between the cylinder head and the upper end face of the fire shoulder of the cylinder liner, remains unoccupied; in addition, the provision of spiral grooves in the cylinder liner is a necessary requirement.
Another internal combustion engine is known (cf. U.S. Pat. No. 3,606,361; IPC F 16 J 15/06) wherein the dead gas volume is occupied by a steel ring having sharp projections on the opposite faces and inserted into a cylinder hole of a cylinder head gasket.
This construction likewise fails to provide for filling the entire volume of the gas space in the cylinder head joint, because unoccupied space remains between the faces of the steel ring, cylinder head and engine block, while the sharp projections may tend to cut into the cylinder head and the engine block in close proximity to the cylinder bore to cause excessive out-of-roundness. In addition, these projections may fail to fit indentations formed during initial mounting of the cylinder head when the latter is remounted, which results in poor sealing.